Conventionally, a fixing device, used for an image forming apparatus such as a copier or printer, where a warming-up time or a first printing time is short and bad fixing may not happen even if a process of the apparatus is made to speed up has been known. See, for example, Japanese Patent Application Publication No. 2008-158482.
More specifically, the fixing device discussed in, for example, Japanese Patent Application Publication No. 2008-158482, there are a fixing belt as a fixing member, a metal member as a facing member, a heater as a heating member, a pressing roller as a pressing member, and others. The metal member having a substantially cylindrical shape is fixed so as to face a part or an entirety of an internal circumferential surface of the fixing member. The heater is provided inside the metal member so as to heat the metal member. The pressing roller presses the fixing belt so that a nip part is formed.
The fixing belt is heated by the metal member heated by the heater so that a toner image on a recording medium conveyed to the nip part receives heat and pressure at the nip part. As a result of this, the toner image is fixed on the recording medium.
In the fixing device discussed in, for example, Japanese Patent Application Publication No. 2008-158482, if a clearance amount (facing distance) between the fixing belt (fixing member) and the metal member is too large, heating efficiency of the fixing belt cannot be sufficiently improved. If the clearance amount between the fixing belt and the metal member is too small, the fixing belt may make sliding contact with the metal member so as to become worn at the time of operation of the image forming apparatus.